A typical Software Defined Networking (SDN) network includes a network controller in a control plane and a SDN switcher in a forwarding plane, respectively called as a controlling device and a data forwarding device. A method for forwarding a data packet in the SDN network utilizes a flow table for data packet forwarding. Specifically, the controlling device controls the data forwarding device by a standardized SDN protocol and distributes the flow table to the data forwarding device; the data forwarding device receives and stores the flow table; when the data packet is received from the network, the data forwarding device checks whether there is a matched flow table entry available in the flow table; if yes, the data forwarding device forwards the data packet according to an operation in the flow table entry; if no, the header information in the data packet is encapsulated as a Packet-in message to be sent to the controlling device through a secure channel, and then the controlling device decides the relevant behavior. OpenFlow is an example of one kind of switching technology, which can be used to establish the above-described SDN network.